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Motorhead Memo: Gasoline Genesis

By Kip Woodring

In 1967, leaded 104-octane premium gasoline went for about 37 cents a gallon. (I know; I was there.) When I filled up a day or so ago, in good ol’ 2007, it was nearly $3.70 for a gallon of what passes for 92-octane “fuel”—not that it was gasoline at all. By the time you read this, it’s likely that fuel costs here in the U.S. will have reached an all-time high—in more ways than one. How the hell did we get here from there? What’s really going on with fuel anyway? I think it’s time we talked…

First, let’s talk about Kettering—Charles F. Kettering to be precise. After all, among his many incredible (and largely unsung) contributions to petrol-powered society, he’s the father of modern gasoline and the dude that friggin’ invented octane. So, please forgive this long preamble, prior to the point (and the parts that should concern you and your Harley) but there isn’t any other way to “string the beads” of a century of fuelin’ around and make sense of all this “better living through chemistry.” (Besides, those who don’t learn from history… y’know?)

In the first years of the automotive age, while steam and electric alternatives were being trounced into eventual (and one would think permanent) oblivion by the overall advantages of gasoline power (and the cheap Model T) all the innovations made on gasoline-powered vehicles were advances in engine technology and physical structure. Other essentials, including the electrical system and engine-fuel combinations, remained far from perfected. Both of those crucial developments were to be the products of one man’s brilliance.

Oil addiction from a conservationist?
Believe it or not the U.S.A. was an oil-exporting nation until nearly 1950. (Actually, we were completely self-sufficient in all forms of energy until the late ’50s!) Domestic oil production didn’t peak until 1970 at 11.3 million barrels per day, yet our usage shot through the roof at the same time. So, in 1970 we imported 3.2 million barrels a day to make up the difference. Today imports are 400 percent higher. Let’s just say that Sloan has a lot more to answer for than Kettering!

1908—Kettering had heard that Cadillac was very dissatisfied with its ignitions, so he sketched out the design of a new, improved system and sold it to Cadillac for installation on 1910 models. It became the standard of the world for the next 70-plus years. Business was good, so in July 1910, he started Dayton Engineering Laboratories Company (Delco) and began work on his second innovation, the first practical self-starter. While others (including Thomas Edison) had tried (and failed), Kettering was undaunted. His solution was simply to devise a compact motor that would deliver a short burst of power. Within six months Kettering perfected a redesigned electrical system that integrated a motor/generator, a storage battery… and electric lighting… to support his “impossible” starter. Cadillac introduced the new system in August 1911 on its 1912 model, and we still use the basic setup today. More importantly, besides broadening the appeal of cars that didn’t require the risk of injury or death, the self-starter also made it possible to offer (you guessed, right?)—larger engines—with more cylinders and higher compression.

1910—Kettering bought a copy of a book titled “The Internal Combustion Engine.” In it, he found a 100-page treatment of the new science of thermodynamics, with an extensive discussion of the relationship between compression ratio and efficiency. The pursuit of thermodynamic efficiency in internal combustion engines was to become Kettering’s lifelong obsession.

He reasoned that the long-term survival of the auto industry depended upon improving engine efficiency—and, unless a solution to the recurring oil shortages in his time could be found, fuel might soon be depleted. Thus, gasoline had to be engineered to be more efficient too. More than perhaps anyone of his time (or the present time), Kettering was a textbook conservationist. He was also a shrewd witness to our inauguration into the automobile age as well as causes and effects with which we still cope.

Experience told Kettering that the solution to oil shortages lay in solving the thermodynamic problem of “knock.” No one had shown what caused knock back then, but it was recognized that it was related to higher engine compression—that is, the ratio of the volume in the cylinder at the bottom of the piston stroke (its most expanded volume) to the volume at the top of the stroke (its most compressed volume). Because the occurrence of knock increased as the compression ratio increased, knock formed a real barrier, an upper limit on an engine’s compression. Truly the last frontier! Back in the day, with gasoline what it was, and engines what they were, knock would begin at about four to one, a compression ratio lower than an old flathead Harley. Most experts had resigned themselves to the inevitability of knock and left compression low, but as usual Kettering decided to defy the experts and find a solution. In the 1910s, conventional wisdom held that knock was caused by “pre-ignition,” meaning ignition of the gasoline in the combustion chamber before the spark plug fired.

One more little obstacle to overcome?
1916—In the very first experiment measuring the knock sequence, it was found that the sharp pressure oscillation associated with knock did not occur before the spark plug fired, but after. Surprise—all the expert theories were mistaken! So, was knock caused by gasoline rather than something mechanical, after all? Sure enough, adding red iodine caused a notable decrease in knock. But, it didn’t take long to realize this phenomenon had nothing to do with color. It resulted from some unidentified chemical property of iodine.

1917—Since the key to aircraft lift and flight distance is maximizing the power-to-weight ratio, engine efficiency is even more critical to aviation than it is to automobiles or motorcycles. High- compression engines could dramatically improve the speed and power of warplanes if the knock problem were solved. It was no surprise then, that at the behest of the War Department, Kettering and his henchmen developed a fuel blend composed of 70 percent cyclohexane (C6H12) and 30 percent benzene (C6H6) that enabled a boost in compression of aircraft engines from 5.5:1 to 8:1. We won!

1919—Delco discovered that aniline (C6H7N) had much better anti-knock qualities than iodine. Kettering presented Delco’s findings in a paper called “More Efficient Utilization of Fuel.” World War I had made the public sensitive to potential energy shortages, so Kettering’s conservation speech addressed a very receptive audience. Besides the shortages during the war, the need for fuel efficiency was underscored by the growth of the civilian vehicle population. From 1912 to 1920 domestic crude oil production had doubled, but the number of autos increased—ninefold! By the late spring of 1920, the U.S. was once again in a severe petroleum shortage.

Getting the lead in!
1921—Aniline turned out to be unacceptable. It corroded engine metals and it oxidized, making sticky and troublesome deposits, not to mention being costly, poisonous and smelly.

On a train from New York, Kettering noticed a newspaper article that reported the discovery of a new substance with potent solvent properties, about five times more effective than aniline, selenium oxychloride (Cl2OSe). A similar substance, diethyl telluride (C2H5)2Te), was less corrosive and four times more effective than selenium. But both of these stunk to high heaven! Most fatally, neither was available in sufficient quantities.

But Kettering’s team was getting closer, and they knew it. To give the research a little direction, they consulted Dr. Robert E. Wilson at MIT, who suggested using Langmuir’s periodic table, organized according to chemical valence. By charting the discoveries they had already made, and the periodic table, suddenly there was a pattern that pointed to lead. To make elemental lead soluble in gasoline they formulated it as tetraethyl lead (Pb(C2Hs)4). On December 9, 1921, they first tested tetraethyl lead and reduction in knock was even more stunning than they’d anticipated: at a concentration of 1 percent, the fuel was entirely free of knock and it didn’t reappear until it was diluted to 1/40th of 1 percent.

1922—Kettering soon recognized that the use of lead additive had two drawbacks that would have to be overcome:
The combustion of tetraethyl lead in the engine produces lead oxide that builds up as a deposit of solid material and causes damage to spark plugs and exhaust valves. To address the deposit problem the laboratory embarked on a new research program to get the lead to leave the engine in the exhaust. They found that lead oxide could be prevented by adding organic halides, specifically soluble compounds of chlorine and/or bromine, to the gasoline along with the tetraethyl lead. During combustion these “scavengers” would combine chemically with the lead and carry it out of the engine. In 1925, they settled on ethylene dibromide (C2H4Br2) as the scavenger.
The use of lead in gasoline had a more dangerous (though apparently less obvious) drawback, its hazard to human health. GM decided to move quickly to introduce gasoline lead additive, thinking it was better to bring a promising product to market quickly than wait for complete resolution of its… uh… niggling little problems.
To give gasoline containing tetraethyl lead a name with character, Kettering decided to call it “Ethyl.” To give Ethyl gasoline a distinctive appearance it was dyed red, in memory of the iodine experiment that opened the door to the future of fuel.

Unlike the deposit problem, which GM could and would resolve privately, the human health hazard was a matter that ultimately had to be decided by public authorities.

1923—Alfred P. Sloan becomes president of GM, which by then owned Delco. Kettering’s original purpose for the anti-knock research gave way to Sloan’s desire to improve engine performance without regard for its effect on fuel economy. Kettering’s anti-knock research had become part of GM’s corporate strategy to make available to the middle class the luxuries, speed and power that had been accessible only to the rich, and along the way knock (if you’ll pardon the expression) Ford out of his market dominance.

On February 1, 1923, at Sixth and Main streets in Dayton, Ohio, GM’s Ethyl Gasoline was first offered for sale. Meanwhile, to avoid having to pay licensing fees to others, Standard Oil of New Jersey developed more efficient methods for producing tetraethyl lead. The problem of knock was solved (until 1973).

1924—GM and Standard Oil pooled their patents to create the Ethyl Gasoline Corporation. “Ethyl” would market gasoline lead additive produced by Standard Oil and DuPont. GM and Standard Oil would each hold half of the equity in the new company. The board appointed Kettering as its president. This was a small beginning, but its implications were already being recognized—among these the not-small fact that for the next several decades, he owner/driver of every subsequent high-performance engine, developed by any manufacturer, in effect paid GM a stipend! Ethyl was also GM’s ace in the hole in the serious and ever-escalating competition for power (with no thought for efficiency!).

Within a few years Ethyl developed the octane scale as a way to measure the anti-knock property of a fuel. Octane, as first defined by Kettering, remains the most important consumer measure of gasoline quality. In terms of both technological merits and its impact on industrial society in general—and our beloved Harleys specifically—this rating has had some astonishing, and far-reaching effects…

…which we’ll get into next month!

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